html, body {
  height: 100%;
}
.bigbox {
  display: flex;
  flex-direction: column;
  height: 100%;
  flex: 1;
  box-sizing: border-box;
  padding: 28px 26px 12px 26px;
}
.flexbox {
  display: flex;
  justify-content: center;
  align-items: center;
}
.flexbox {
  display: flex;
  justify-content: space-between;
}
.leftBox {
  width: 322px;
}
.rightBox {
  flex-grow: 1;
}

.bottomBox {
  /* 绝对定位居中 */
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  bottom: 0px;
  height: 70px;
  box-sizing: border-box;
  padding: 13px 10px;
  display: flex;
}